GB333209A - Electromagnets - Google Patents

Abstract

333,209. Sokoloff, B. N. May 3, 1929. Electromagnets.- The armature of an electromagnet of the pot or yoke type consists of a number of separate portions, relatively movable and serially arranged in a single air gap. Fig. 1 shows three such portions 5, 6, 7 moving in a nonmagnetic sleeve 11 within a coil 6 having pole-pieces 1, 4 connected by a magnetic casing 3. To the piece 5 is secured a rod 8 of nonmagnetic material formed with shoulders against which the pieces 6, 7 bear. When the magnet is not excited, the space between the pole-piece 4 and the piece 7 is less than that between the piece 7 and the piece 6, which is less than that between the piece 6 and the piece 5. When the magnet is energized the piece 7 comes in contact with the pole-piece, then the piece 6 with the piece 7 and the piece 5 with the piece 6. The magnet may be energized by currents of strengths corresponding to these three stages. Fig. 7 shows the invention applied to a power hammer &c. The pieces 39, 45, 44 of the armature are carried on the shouldered and nonmagnetic piece 46 which strikes the head of the tool 57. The pole-pieces 31, 32 are laminated and held together by endpieces and bolts and connected magnetically by a casing 35 of corrugated sheet-metal slotted to lessen eddy-currents. The armature is returned by a spring 42, which may be of such strength that the return may take longer than the power stroke, and the length of the stroke is regulated by a screw 58. The winding is in two portions 59, 60 of different numbers of turns and connected in parallel. This is stated to reduce sparking.